Lifetime determination of theFeXIV3s23pP3∕2o2metastable level

Abstract

The lifetime of the $3{s}^{2}3p\phantom{\rule{0.2em}{0ex}}^{2}P_{3∕2}^{o}$ first excited energy level of $\mathrm{Fe}\phantom{\rule{0.2em}{0ex}}XIV$ (Al like) was measured at the Heidelberg electron beam ion trap by monitoring its optical decay to the ground state by a magnetic dipole $(M1)$ forbidden transition at $\ensuremath{\lambda}=530.29\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$ (green coronal line), a well-known line in stellar spectra. A new trapping scheme has been applied. Possible systematic effects were investigated by studying the dependence of the decay curves on various trapping conditions with high statistical significance. The result of ${16.726}_{\ensuremath{-}0.010}^{+0.020}\phantom{\rule{0.3em}{0ex}}\mathrm{ms}$ shows an unexplained discrepancy in the average value of existing theoretical predictions. The inclusion of the electron anomalous magnetic moment within the theoretical calculations increases this disagreement, thus pointing at other possible origins of this discrepancy.